The present technique relates to a gain control circuit and a receiving system. Specifically, it relates to a gain control circuit in a receiving device and a receiving system.
In an existing receiving device that receives ground waves and so forth, the level of a received signal is often unstable. Therefore, an auto gain control (AGC) function is frequently provided to amplify or attenuate the level of the received signal so that the level of an output signal may be kept constant. Such a receiving device supplies a signal controlled to a constant level to an apparatus such as a demodulating device. In this demodulating device or the like, generally an allowable voltage under which avoidance of malfunction and failure is ensured is lower when its size is smaller. In recent years, the allowable voltage of the apparatus tends to be low because size reduction thereof is being promoted particularly.
To protect such an apparatus, there has been proposed e.g. an amplifying circuit that performs voltage division of the amplitude of the output signal to limit the output voltage to at most the allowable voltage of the apparatus (refer to e.g. Japanese Patent Laid-open No. Sho 60-000109).